66 lines
3.0 KiB
Plaintext
66 lines
3.0 KiB
Plaintext
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In mechanical drawing, it's common to use a parallel projection of a
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3d model into a 2d drawing. A parallel projection is also known as an
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axonometric projection; orthographic, isometric, dimetric, and trimetric
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projections are examples of such a projection. In a parallel projection,
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any two lines that are parallel in real life must also appear parallel
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on the drawing.
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This differs from a perspective projection. In a perspective projection,
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objects that are closer to the "camera" appear larger than objects
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that are farther away. This means that some lines that are parallel in
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real life will not be parallel on the drawing; they will converge at a
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vanishing point. This may cause confusion.
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By default, NTsolver displays a parallel projection of the model. To
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display a perspective projection, choose #LINK(configuration) in the text
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window, and set the perspective factor to something other than zero.
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The distance from the "camera" to the model is equal to one thousand
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pixels divided by the perspective factor.
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The user interface consists of two windows: a large graphics window that
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displays the model being drawn, and a smaller text window, that displays
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information about the model.
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After starting a new file, the model is empty except for the three
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coordinate planes. The graphics window's view is aligned so that the XY
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plane is parallel to the plane of your monitor.
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NTsolver requires a mouse with a scrollwheel or center button. To pan
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the view to the left or right, center-drag the mouse. To rotate the view
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around the horizontal or vertical axes of the screen, shift-center-drag
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the mouse. To rotate the view around the axis perpendicular to the screen,
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control-center-drag the mouse.
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After moving the view, it's possible to orient the view back on to the
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active workplane. Choose #MENU(Sketch -> Draw in Workplane), or press
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#KEY(W). This produces an orthographic projection of the model. When
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drawing lines and curves in a workplane, it's convenient to work with
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the view oriented on to that workplane.
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To zoom in, rotate the mouse wheel, or choose #MENU(View -> Zoom In /
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Out). This will not have any visible effect until a model has been
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drawn, though, since the coordinate planes are automatically scaled to
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fit on-screen.
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The text window works like a web browser; any underlined text is a link,
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which may be activated by clicking on it. At the top of the text window,
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two rows of links will show and hide different features of the sketch
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(workplanes, normals, points, constraints, shaded, faces, mesh, hidden
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lines).
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Below that, the text window displays a list of groups. A group is a set of
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entities, like lines, circles, or planes. In a new file, two groups exist:
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the references, and a drawing group. The references are the coordinate
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planes (XY, YZ, and ZX); they provide the initial geometric entities to
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constrain against. The drawing group is active; if you draw a line, or
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a rectangle, or some other new geometry, then that geometry will appear
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in the active drawing group.
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To start, we
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